Bad beef will have a sheen to it, like slime coating that is iridescent in the light. And a very pungent odor! If you had to get yoru nose very close it it to smell anything, it's just fine. Go ahead and use it. BTW: aged beef is refrigerated for 30 days at least after slaughter.
High CPK levels are an indicator of a variety of muscle diseases and problems, not just Rhabdo. The 'normal' CPK levels are between 25 and 170. Over this number, and you have muscle cell damage happening. You can have high(er) CPK levels and not have Rhabdomyolysis. You can have muscle cell death happening, and never get to Rhabdomyolosis. You have to have -enough- cell death and -enough- myoglobin and other toxic dead cell byproducts to overwheml the system.
Rhabdomyolysis is the breakdown of damaged skeletal muscle. Muscle breakdown causes the release of myoglobin into the bloodstream. Myoglobin is the protein that stores oxygen in your muscles. If you have too much myoglobin in your blood, it can cause kidney damage. About 26,000 cases of rhabdomyolysis are reported in the United States each year.